Description:

Improvements in the environmental impact of the pharmaceutical and
agricultural chemical industries have lagged improvements seen in the synthesis
of bulk commodity chemicals. Fine chemicals are typically prepared by multistep
reactions that use stoichiometric reagents and chiral auxiliaries. The atom
economy of these syntheses is poor. Because many biologically active compounds
from the pharmaceutical and agricultural chemical industries are highly
oxygenated and prepared from simpler compounds by some type of oxidation
reaction, there is a need for more selective oxidation catalysts.

This project will promote the environmentally responsible synthesis of fine
chemicals through the development of a series of catalysts for the selective
oxidation and modification of substrates. This will improve atom economy and
reduce waste in one of the fastest growing areas of the chemical industry. By
varying the metals and their ligands in heterometallic complexes {M(N)R2}2(µ -S)2M"Lx and
[N(n-Bu)4][M(N)R2}(µ -O)2M'O2], we will create a "toolbox" of
complexes with a range of steric and electronic properties.

Replacing petroleum-based feedstocks with renewable feedstocks from
agricultural sources would reduce our dependence on foreign oil reserves, reduce
the net release of CO2 into the atmosphere, and promote the
agricultural industry in the United States. In order to use corn and
soybean-derived compounds in the synthesis of fine chemicals, we must develop
new, selective methods for their modification. In this project we focus on
catalyzing oxidative transformations of fatty acids from corn and soybean oil,
isoflavones from soy, and steroids from these plant sources. We will also
prepare water-soluble catalysts for the oxidation of carbohydrates.

To lessen the need for volatile organic compounds as solvents, we will
examine supercritical carbon dioxide as a reaction solvent. We will
"heterogenize" some catalysts by attaching molecular species to an insoluble
support. This should aid in the separation of catalyst from the product.

The first objective of this project is to synthesize a series of new heterometallic oxidation catalysts with a range of steric and electronic properties. Some complexes will be chiral to catalyze asymmetric oxidation reactions. Our goal is to prepare a "toolbox" of catalysts that would each be effective for the oxidation of only one functional group in a particular substrate. Molecular oxygen will be the only stoichiometric oxidant used. A second objective is to find methods for the chemical transformation of agricultural products to fine chemicals. We will test our new heterometallic complexes as catalysts for oxidative transformations of fatty acids from corn and soybean oil, isoflavones from soy, and steroids from these plant sources. We will also prepare water-soluble catalysts for the oxidation of carbohydrates. The final objective is to reduce the quantity of volatile organic solvents used in oxidation reactions. We will test water-soluble complexes for catalytic activity in water. Some complexes will be tested in alternative solvents, such as supercritical CO2. Supported metal complexes will be tested as heterogeneous catalysts.

Approach:

We will generate a family of potential lipid oxidation catalysts of the formula
{M(N)R2}2(µ -S)2M"Lx or [N(n-Bu)4][M(N)R2}(µ -O)2M'O2] by methods similar to those we have
previously used to synthesize {Ru(N)Me2}2(µ-S)2Pt(dppe). Each new complex will be
fully characterized and surveyed for oxidation of a range of substrates in the
presence of molecular oxygen. Products will be quantified by GC or HPLC
techniques. Those heterometallic complexes that prove to be selective oxidation
catalysts in the initial survey will be examined as catalysts for the oxidation
reactions of selected plant steroids, isoflavones, and carbohydrates with
molecular oxygen. We will isolate the organic products and use NMR spectroscopy, mass spectrometry, and elemental analysis to characterize them.

Expected Results:

The results from this proposal would relate to the Technology for a
Sustainable Environment program section 2.2.1: Chemistry and Chemical
Reaction-based Engineering for Pollution Avoidance or Prevention. The design of
more selective catalysts for the oxidation of organic substrates would greatly
reduce waste. The use of molecular oxygen for these oxidations would reduce the
chemical hazards associated with other oxidizing agents. The development of
methods for the catalytic transformation of agricultural products into fine
chemicals would reduce our need for non-sustainable, petroleum-based feedstocks.

Estimated Improvement: Successful completion of the work will lead to
higher efficiency and lower waste in the production of fine chemicals.

The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.